Accoustic Buoy

ABSTRACT

A buoy provided preferably for ascending in the water from an initial submerged position. The buoy comprises a buoyancy element positioned at an upper portion of the buoy in the ascending direction. Further the buoy comprises a storing structure for an elongated member positioned below the buoyancy element in the ascending direction, wherein one end of the elongated member is connected to the buoy and the other end of the elongated member is connected to an object submerged in the water. The buoyancy element is provided to obtain a rotation of the buoy around its central axis thereby paying out the elongated member while the buoy is ascending essentially vertically in the water.

The invention concerns a buoy which is provided for ascending from asubmerged position in the water. However the principles of the inventionmay also be applicable to a buoy which is prepared for descending.

The buoy can be used for providing access to a submerged object such asfor instance an anchor, a lump weight, a heavy weight hawser or anyother object to be submerged in the water. In an initial position thebuoy is submerged in the water and connected at a fixed distance bysuitable means to the submerged object.

In accordance with prior art it is common knowledge to provide asubmerged object with a buoy arranged for rising in the water whenreleased from the submerged object.

U.S. Pat. No. 3,755,836 discloses a submarine provided with acommunication buoy to be sent from the submarine to the surface of thewater. One end of an umbilical cord is attached to the submarine and theother end of the umbilical cord is attached to the positive buoyancybuoy rising in the water.

Other buoys to be placed in a submerged position are disclosed in U.S.Pat. No. 4,954,110 and U.S. Pat. No. 3,793,623.

In accordance with the invention an elongated member such as forinstance a line, rope, cable, wire provides a connection between thebuoy and the submerged object.

The buoy has means for the storing of an elongated member such as aline. For simplification the elongated member will in the following bereferred to as a line. The skilled person will understand that alldevices fitting into the term elongated member may be used with the buoyin accordance with the invention. One end, that is the free end of theline, is connected to the submerged object, the other end is attached tothe buoy. Initially while the buoy is submerged at a position close tothe submerged object most of the line is stored in the buoy. The freeend of the line stays connected to the submerged object while the buoyascends in the water giving out line from the buoy as the buoy rises inthe water.

Prior art describes solutions wherein a buoy is arranged to ascend froma submerged position paying out line along with the ascendance in thewater. To avoid a tangled line during pay out of the line some parts ofthe buoy in accordance with prior art, had to be arranged movablerelative to the other parts of the buoy. This may be achieved forinstance by winding the line on a drum which is able to rotate relativeto the other parts of the buoy.

It is an object of the current invention to provide a solution with nomoving parts where the line is given out/paid out from buoy without theline being tangled or twisted.

The object of the invention is obtained by the invention as defined inthe independent claim, wherein further embodiments are defined independent claims.

In accordance with the invention a buoy is provided preferably forascending in the water from an initial submerged position. The initialposition may be on or close to the bottom of the ocean, or somewherebetween the bottom and the surface of the water. The buoy comprises abuoyancy element positioned at an upper portion of the buoy, seen in theascending direction of the buoy. The buoyancy element preferablyprovides net positive buoyancy to the buoy, this may be accomplished byany conventional manner known to the skilled person. The buoy furthercomprises a storing structure for an elongated member such as a line,which storing structure is positioned below the buoyancy element in theascending direction. One end of the elongated member is connected to thebuoy and the other end of the elongated member is connected to an objectsubmerged in the water. The submerged object is preferably positioned atthe sea bottom.

The buoy is characterized in that the buoyancy element is provided toobtain a rotation of the buoy around its central axis thereby paying outthe elongated member while the buoy is ascending essentially verticallyin the water. The buoy is arranged so that an essentially verticalequilibrium position is maintained when the buoy is ascending in thewater. An unbalance is introduced in the buoyancy element causing thebuoy to rotate around its axial axis/central axis due to the effect of amoment.

The buoy comprises parts which are fixed relative to each other, therebyobtaining a buoy with non-movable parts. The storing structure may beconstituted by a drum which is arranged fixed or semi-fixed to thebuoyancy element. The drum may comprise two drum wheels and a reelarranged in between and fixed to the drum wheels. The line is coiled uponto the drum, preferably around the reel. An axial axis of the reel maybe arranged parallel or in line with the axial axis of the buoy. Thebuoy thereby provides an arrangement where there is no relative movementbetween the various parts of the buoy. When the buoy starts rising inthe water the buoy is forced to rotate due to the arrangement of thebuoyancy element and the line is unwinded/paid out from the buoy.

The buoyancy element may be arranged in different ways to obtain arotation of the buoy. In one embodiment the buoyancy element is providedto function as a propeller while ascending in the water and may be givenvarious shapes to lead the water through the buoyancy element andcausing a rotation of the buoy. The buoy may be caused to rotate even ifthe buoyancy element is provided with only one projecting structure.

The buoyancy element may assume various shapes, for instance thebuoyancy element may assume a disc or a cylindrical shape.

In one embodiment of the invention the buoyancy element is arranged withrecesses arranged inclined to the central axis of the buoy. The recessesmay for instance be arranged as channels in the buoyancy element or maybe provided in between projecting structures arranged onto the buoyancyelement. Each recess has an inlet opening and an outlet opening whereinthe inlet and outlet are placed at two different positions with adistance in between in the circumferential direction which may be equalor vary between two and two recesses. Viewed in a radial plane the inletand the outlet are positioned with an angle distance in between.

The recesses may be placed at various positions within the outercircumference of the buoyancy element. In one preferred embodiment eachrecess is arranged with a radial distance to the central axis whichradial distance is equal or varies along the longitudinal direction ofthe recess. In one further preferred embodiment each recess is placedclose to the circumference and has an open side surface in an outeraxial side surface of the buoyancy element, which axial side surface ispositioned at a radial distance from the central axis of the buoy.Further the recess has the inlet opening positioned in the top surfaceof the buoyancy element and the outlet opening positioned in the bottomsurface of the buoyancy element.

When the recess is arranged with a radial distance to the central axiswhich varies along the longitudinal direction of the recess, the recessmay be provided with an inlet opening in the top surface and an outletopening in the outer axial side surface of the buoyancy element. In thisembodiment the radial distance to the central axis decreases as therecess approaches the top surface.

The buoy may be provided with a release mechanism preferably a hardwire,a timer or an acoustically controlled release mechanism to release thebuoy from the initial submerged position.

The buoy may be provided with at least one additional buoyancy elementpreferably positioned at the lower portion of the buoy in the ascendingdirection.

A transponder may be included in the buoy, preferably that the buoyancyelement is arranged at a radially outer position coaxially to thetransponder. Further, the reel of the drum may be arranged below thebuoyancy element at a radially outer position coaxially to thetransponder. The transponder is thereby protected by the various partsof the buoy.

FIG. 1 illustrates the buoy used in a pick-up situation.

FIG. 2 is a detailed illustration of situation shown in FIG. 1.

FIG. 3 is a concept illustration of the buoy 5 shown in FIGS. 1 and 2.

FIGS. 4 and 5 show the buoy arranged with recesses.

FIG. 6 show the buoy with alternative recesses.

FIG. 1 shows a vessel 1 having located a submerged object 2. The object2 is attached to a heavy weight object such as an anchor 3 by an anchorline 4. When the submerged object 2 is located, a signal such as anacoustic signal is sent to a buoy 5, also submerged and connected to thesubmerged object 2 at a fixed distance to the submerged object 2. Thebuoy is provided with a coiled up line 6 having one free end fixed tothe submerged object 2. Whereupon receiving the signal the buoy isallowed to give out line while ascending in the water until reaching thesurface position as illustrated in FIG. 1. The buoy is ready to bepicked up by the vessel and may be provided with a pick up buoy 7 asshown in FIG. 2 to facilitate picking up the buoy 5. The submergedobject 2 is thereafter retrieved from its submerged position.

The buoy 5 is constituted of a buoyancy element 8 and a storingstructure 9, which may be arranged onto a transponder 10 as shown inFIG. 3. The buoyancy element 8 is positioned at the upper portion of thebuoy 5. The transponder is protected by a cage element 10 a.

FIG. 4 shows the buoy 5 provided with the buoyancy element 8 and anadditional buoyancy element 11 at the lower portion of the buoy 5. Thestoring structure 9 comprises a reel 9 a and two drum wheels 9 b. Theline 6 is coiled up onto the reel 9 a. The buoyancy element 8 isprovided with recesses 8 a arranged inclined in the outer axial surface8 b. The recesses have openings in the outer axial surface 8 b and inthe top and bottom surfaces 8 c, 8 d of the buoyancy element 8. Thebuoyancy element is further provided by a protection cage 10 a. When thebuoy 5 is released from its submerged position, the buoy ascends in thewater due to net positive buoyancy of the buoy provided essentially bythe buoyancy element 8. During the ascendance in the water the buoymoves essentially vertical. While ascending the buoy is made to rotatearound its central axis 5 a due to the water led trough the inclinedrecesses 8 a arranged in the buoyancy element 8. This rotation of thebuoy 5 causes the line 6 (not shown) to unwind untangled from the reel 9a. The free end of the line 6 stays connected to the submerged object 2during the unwinding of the line from the reel 9 a.

The rotation of the buoy 5 is illustrated by arrows 12 and the waterflowing through the recesses 8 a is illustrated by arrows 13.

FIG. 5 shows the buoy exploded. The buoyancy element 8 is constituted bytwo sections to be mounted around the transponder thereby providing abuoyancy element with a cylindrical shape. The additional buoyancyelement 11 is also constituted by two sections to be mounted around thetransponder thereby providing a buoyancy element with an annular shape.

FIG. 6 shows the buoy provided with alternative inclined recesses 8 a.Each recess 8 a has an inlet opening in the outer axial surface 8 b andan outlet opening in the top surface 8 b. The line 6 is shown windedonto the reel.

1. A buoy (5) provided for ascending or descending in water from aninitial submerged position, which buoy (5) comprises a buoyancy element(8) positioned at an upper portion of the buoy (5) in the ascendingdirection, a storing structure (9) for an elongated member (6)positioned below the buoyancy element (8) in the ascending direction,wherein one end of the elongated member (6) is connected to the buoy (5)and the other end of the elongated member (6) is connected to an object(2) submerged in the water, characterized in that the buoyancy element(8) is arranged such that a torque, caused by the water, acts on thebuoyancy element (6) when the buoy (5) is ascending in the water, thetorque causing a rotation of the buoy (5) around its central axis (5 a),the elongated member (6) thereby being paid out while the buoy (5) isascending in the water.
 2. The buoy in accordance with claim 1,characterized in that the buoy (5) comprises parts which are non-movablerelative to each other, the storing structure (9) being constituted by adrum which is arranged non-rotatably fixed to the buoyancy element (8).3. The buoy in accordance with claim 2, characterized in that the drumcomprises two drum wheels (9 b) and a reel (9 a) arranged in between andfixed to the drum wheels (9 b), and that an axial axis of the reel (9 a)is arranged parallel or in line with the axial axis of the buoy (5). 4.The buoy in accordance claim 1, characterized in that the buoy isprovided with at least one additional buoyancy element (11) positionedat the lower portion of the buoy (5) in the ascending direction.
 5. Thebuoy in accordance with claim 1, characterized in that t the buoyancyelement (8) is provided to function as a propeller.
 6. The buoy inaccordance with claim 1, characterized in that the buoyancy element (8)has a disc or cylindrical shape.
 7. The buoy in accordance with claim 1,characterized in that the buoyancy element (8) is arranged with recesses(8 a) arranged inclined to the central axis of the buoy, wherein eachrecess (8 a) is arranged with a radial distance to the central axiswhich is equal or varies along the longitudinal direction of the recess(8 a).
 8. The buoy in accordance with claim 7, characterized in thateach recess (8 a) has an open side surface in an outer axial surface (8b) of the buoyancy element (8), and an opening in the top (8 c) and thebottom (8 d) surface of the buoyancy element.
 9. The buoy in accordancewith in accordance with claim 7, characterized in that each recess (8 a)has an opening in the top surface (8 c) and the outer axial side surface(8 b) of the buoyancy element (8).
 10. The buoy in accordance with claim1, characterized in that the buoy is provided with an acousticallycontrolled release mechanism to release the buoy (5) from the initialsubmerged position.
 11. The buoy in accordance with claim 1,characterized in that the elongated element (6) is constituted by aline, a cable having a free end connected to an object (2) positioned atthe sea bottom.
 12. The buoy in accordance with claim 1, characterizedin that a transponder is included in the buoy.
 13. The buoy inaccordance with claim 12, characterized in that the buoyancy element (8)is arranged at a radially outer position coaxially to the transponder.